How to stop an application which is not responding

Sometimes applications just freeze for either a good reason or no reason at all. Here is how to terminate a freezing application.

Let’s start this tutorial by starting Firefox. So now that the Firefox is running. We can type either a ps or top command on the terminal to see the running applications. So when I type for example the following command:

ps aux

It gives e a list of running applications, processes and so on. I can see that I have a Firefox running:

n00bsai+  173877 18.9  2.5 3730772 819744 ?      Sl   15:52   0:19 /usr/lib/firefox/firefox --new

The process ID is: 173877 and to sort of verify that I can run the following command:

ps aux | grep "firefox"

This basically gives me the same result, but it filters the applications, processes and so on, by name. This time the filter is Firefox.

n00bsai+ 173877 6.1 2.0 3666304 678904 ? Sl 15:52 0:25 /usr/lib/firefox/firefox --new-window

Now we can be quite certain that the Firefox’s process ID = 173877.

Now let’s pretend that the Firefox has frozen and doesn’t respond to anything. Now we can sort of force kill it or shut it down, with the following command:

kill -9 173877

Now we can see that the Firefox is no longer running.

If you have followed along with this tutorial, your Firefox’s process ID is definitely different, so you need to change the above command so it looks more like this:

kill -9 (process ID aka PID)

replace the process ID aka PID with your process number and you can get it with the ps aux command or top command. I recommend the ps command, because then the processes doesn’t jump.